Just in case you didn't catch it, propane fuel would liquify in the chamber at above 204x or so, depending on temperature. Until that point, since propane produces more energy per chamber volume than hydrogen, hydrogen is pointless, and an unneccesary hazard.

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Spudfiles' resident expert on all things that sail through the air at improbable speeds, trailing an incandescent wake of ionized air, dissociated polymers and metal oxides.

well, if you have a car battery you could do electrolosis with an anode and a cathode (something aluminum and something copper) and just collect the gases into a ballon, but you'd have to do this every time you want to fire it off

Given that the OP hasn't answered the "Why can't you get propane?" question I'm leaning towards the answer being, "Because my mom would start asking questions (whereas hydrogen can be had via electrolosis... no questions!)."

You can always just use a cheapo butane lighter. For $0.99 you get pretty much everything you need (assuming you have some wire laying around that you can strip the insulation from for the feed tubing.)

Because it will be like the camp, and i don't want yo return home to get fuel for my gun. I will be in the forest? near the river, and i need to make the fuel on the place. So propane with oxygen will be tho most powerful gas, or hydrogen. And i have metall pipes, so what i need to do with them? Buy adapters, or weld them?

bobrofilin wrote:Because it will be like the camp, and i don't want yo return home to get fuel for my gun. I will be in the forest? near the river, and i need to make the fuel on the place. So propane with oxygen will be tho most powerful gas, or hydrogen. And i have metall pipes, so what i need to do with them? Buy adapters, or weld them?

That writing makes my head and eyes hurt.

Like I said before, go with disposable butane lighters. A single lighter is enough for at least tens of shots from a typical sized gun.

You don't need to take oxygen with you, unless you are planning on camping on the moon.

bobrofilin wrote:Because it will be like the camp, and i don't want yo return home to get fuel for my gun.

Let me get this straight....

You're gonna haul your spud gun camping. So along with all the food, tents, and everything else you're throwing into your car you're going to bring along a spud gun and (presumably) a sack of potatoes... And yet somehow you can't find room in that car for a 16 oz. disposable propane tank?